Neil Warnock’s Leeds went in 1-0 up at the break after Luciano Becchio finished a counter-attack in the 37th minute.
But the Blues equalised just two minutes after the restart through Juan Mata, before Branislav Ivanovic nodded the Londoners into the lead from a corner in the 64th minute.
Goals from Victor Moses, Eden Hazard and Fernando Torres then added gloss to the scoreline as Rafael Benítez’s men bounced back from their Fifa Club World Cup final defeat by Corinthians on Sunday.
“We upped it in the second half,” Lampard told Sky Sports. “In the first half we weren’t at our best, we were a bit slow with the tempo of the game.
“We gave away a silly ball which allowed them to score. But once we upped our game you could see a big difference.
“We had a word with ourselves at half time and the early goal gave us an impetus to go on and win it.
“Every trophy is a big deal for us, when we look back after our careers finish, we will look back on all our trips to Wembley.”
Man-of-the-match Mata added: “It is tough to play against a team like Leeds. Maybe we did not have enough time to rest [after the Club World Cup] but we showed the desire to win the trophy in the second half. It is a difficult stadium to play in, they have a physical team.”
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